As disclosed in the Patent Document 1, by way of example, a known airbag includes a joint region that joins outer circumferential edges of a pair of walls together. The joint region is formed by placing a sealing member, which has elasticity and has adhesiveness in an unsolidified state, between the outer circumferential edges of the pair of walls, and sewing the outer circumferential edges together with sewing threads such that the threads penetrate an application area of the sealing member.
The sealing member is used for the purpose of preventing gas leakage from the joint region at airbag deployment. Generally, a main cause of gas leakage of an airbag at deployment is a gas leakage from holes which are formed by stitching the walls with sewing threads (i.e. from gaps formed between the sewing threads and the walls). In the above known airbag, the sealing member is applied to the outer circumferential edge of one of the wall, the other wall is then laid over the former before the sealing member is solidified, and then the outer circumferential edges of the pair of walls are joined together by running the sewing threads through the application area of the sealing member. In this conventional airbag, since the sealing member having elasticity is adhered to both of the walls and stops a space between the walls, it covers the sewing threads in the space all over. That is, the sealing member stops the gaps formed between the sewing threads and the walls of the airbag (i.e. the holes formed by stitching the walls with the sewing threads), thus preventing a gas leakage from the gaps formed between the sewing threads and the walls of the airbag.